From my little experience, failed projects are those who run some features but failed to pull through with their WP or roadmap. If tokens dump after they're listed, it's a normal thing to me as early investors always take profit quickly to reenter  trades. That's isn't a sign of a failed project. Sometimes, these dumped projects recover once they've used cases embedded in them.

Any project that doesn't have a problem it's addressing simply doesn't have utility. Such a project should be avoided because it doesn't have potential. Always look out for a use-case token/coin while investing. They're the potential projects.